Reaction for producing an olefin such as propylene or the like from methanol and/or dimethyl ether by the use of a crystalline aluminosilicate as the catalyst is well known. Non-Patent Reference 1 describes production of olefins from methanol and dimethyl ether in the presence of a crystalline aluminosilicate catalyst having an MFI-type crystal structure. The reaction results described therein include a conversion from methanol and dimethyl ether of from 9.1 to 47.5% and a propylene selectivity of 26.7 to 48.2%; and production of ethylene, butene, paraffins and aromatic components is described therein.
Patent Reference 1 discloses a method for producing an olefin from methanol and/or dimethyl ether by the use of a pentasil-type crystalline aluminosilicate having a silicon/aluminium atomic ratio (hereinafter this is expressed as Si/Al ratio in the specification of the present invention) of at least 10, as the catalyst, wherein the total pressure is from 10 to 90 kPa and the weight ratio of water/methanol is from 0.1 to 1.5. The reference says that the method produces at least 5% by weight of ethylene, at least 35% by weight of propylene and at most 30% by weight of butene, but says that the olefin yield under normal pressure is low and paraffin components and aromatic components such as gasoline and the like are produced as by-products in large quantities. The pentasil type is meant to indicate zeolite having a pentasil structure such as MFI type, MEL type, MOR type, etc.
Specifically, the propylene synthesis reaction from methanol and/or dimethyl ether using a crystalline aluminosilicate as the catalyst produces olefins such as ethylene, butene, paraffins such as methane, ethane, propane, butane, and aromatic components as by-products, except the intended propylene.
According to the description in Non-Patent Reference 2, olefins having 4 or more carbon atoms such as butene of the products except propylene could be converted into propylene by the use of a crystalline aluminosilicate as the catalyst. Accordingly, olefins having 4 or more carbon atoms such as butene can be recycled into the reactor for propylene production from methanol and/or dimethyl ether, and can be converted into propylene. On the other hand, paraffins such as methane, ethane, propane, butane, and ethylene have a lower reactivity than olefins having 4 or more carbon atoms, and therefore, even when recycled into the reactor for propylene production from methanol and/or dimethyl ether, they could not almost be converted into propylene. In addition, propane having a boiling point close to that of propylene, and is therefore defective in that, when the propane production amount increases, then the number of the necessary stages of the distillation column increases and the purification energy cost therefore increase. Further, it is known that the aromatic components are converted into coke that fills the pores of crystalline aluminosilicate to lower the catalytic performance thereof. Non-Patent Reference 3 says that ethylene is produced in the elimination reaction from aromatic compounds.
Accordingly, for propylene production from methanol and/or dimethyl ether, preferred is a catalyst with which the production amount of ethylene, paraffins and aromatic compounds is small, and especially desired is development of a catalyst with which the production amount of ethylene and propane is small.
In general, a crystalline aluminosilicate is hydrothermally produced as a powder thereof having a particle size of around 1 micron or so, starting from an aqueous reaction slurry comprising a silicon compound, an aluminium compound, an alkali metal compound, and a structure directing agent such as tetrapropylammonium hydroxide. Accordingly, for use as a fixed bed catalyst, the compound must be fabricated into a shaped body having a size of around 5 mm, and for use as a fluidized bed catalyst, it must be fabricated into a shaped body of secondary particles having a size of from 50 to 100 microns. In the case, in general, the compound is fabricated with a binder such as clay, alumina or the like.
As a crystalline aluminosilicate shaped body not substantially containing a binder component, there is known a shaped body as produced according to a dry gel conversion process (hereinafter this is referred to as a DGC process in the present specification). Patent Reference 2 discloses a method for producing a crystalline microporous material from a solid component that is precipitated from an alkaline inorganic material mixture liquid containing a crystallization regulating agent (structure directing agent) such as an ammonium ion or an amine, a silicon dioxide (SiO2) component and an aluminium salt.
Patent Reference 3 discloses a binderless MFI-type crystalline aluminosilicate shaped body in which the aluminium content outside the crystal lattice of the binderless crystalline aluminosilicate is at most 3% of all aluminium in the shaped body thereof, and an amination reaction catalyst containing the binderless MFI-type crystalline aluminosilicate shaped body.